Re: comparing version numbers

[David Bateman]

Soren Hauberg wrote:

>tor, 23 03 2006 kl. 23:34 +0100, skrev Soren Hauberg:
>  
>
>>tor, 23 03 2006 kl. 17:22 -0500, skrev John W. Eaton:
>>    
>>
>>>If there is a need to compare version numbers, then perhaps we should
>>>have a function to do it that can handle things like 2.9.5+ or
>>>2.9.5+SVN-serial-number (or similar).
>>>      
>>>
>>There is a function for comparing version numbers in the package system I 
>>sent you a while back. I don't think it supports anything else than numbers,
>>but it might provide a starting base. (I don't have the source in front
>>of me, so I can't say what should be changed)
>>    
>>
>Okay, so I found the source and modified it a bit to make the function a bit 
>more general than what was needed in the package system. The attached function 
>supports version strings such as 2.9.5-Whatever.
>
>Two things should be noted:
>  1) It acts like strcmp in C, i.e it returns -1 if the first version
>string is "smaller" than the second, 0 if they are "equal", and 1
>otherwise. I say "equal" (and "smaller") because 2.6 == 2.6.0
>  2) The function doesn't work :-)
>I need to be able to compare strings like I can in C using strcmp. Is
>there an easy way to do this?
>  
>
Why not use something like

text = !strcmp (text1, text2);
if (text)
  texts = sort([text1;text2]);
  if (strcmp(deblank(texts[1,:]),text1)
    text = -1;
  else
    text = 1;
  endif
endif

Though I believe you must be careful with the strsort function of
octave-forge which dispatches to sort. The fact is the 2.9.x sort
function treats strings correctly and strsort.m should probably
therefore be dropped.

D.

>/Soren
>  
>
>------------------------------------------------------------------------
>
>## Copyright (C) 2006 Soren Hauberg
>## 
>## This program is free software; you can redistribute it and/or modify
>## it under the terms of the GNU General Public License as published by
>## the Free Software Foundation; either version 2 of the License, or
>## (at your option) any later version.
>## 
>## This program is distributed in the hope that it will be useful,
>## but WITHOUT ANY WARRANTY; without even the implied warranty of
>## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>## GNU General Public License for more details.
>## 
>## You should have received a copy of the GNU General Public License
>## along with this program; if not, write to the Free Software
>## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
>
>## -*- texinfo -*-
>## @deftypefn {Function File} {} compare_version (@var{v1}, @var{v2})
>## Compares two version strings, returning 0 if they are equal, 1 if
>## @var{v1} is larger (i.e. more recent) than @var{v2}, and -1 otherwise.
>##
>## A version string is a string that describes the version of a piece of
>## software. This function supports the most common type of version strings 
>## found in Free Software, i.e. "Major.Minor.Revision-Text". In this format
>## Minor, Revision and Text are optional, but for clarity it is recommended
>## to at least provide Minor and Revision. If Minor or Revision is not 
>## given, they default to 0, while Text defaults to the empty string. Hence
>## the following is true,
>## @example
>## 2.6 == 2.6.0 < 2.6.0-SVN < 2.6.1
>## @end example
>## @end deftypefn
>
>function [ ret ] = compare_version (v1, v2)
>  ## Both arguments must be strings
>  if (!ischar(v1) || !ischar(v2))
>      error("compare_version: Both input arguments must be strings.");
>  endif
>  
>  ## Split the strings into parts X.Y.Z-TEXT
>  [major1, minor1, rev1, text1] = get_parts(v1);
>  [major2, minor2, rev2, text2] = get_parts(v2);
>  
>  ## Gentleman, start your comparing...
>  major = sign(major1 - major2);
>  minor = sign(minor1 - minor2);
>  rev = sign(rev1 - rev2);
>  text = !strcmp(text1, text2); % XXX: This is just plain wrong! (But it'll 
> have to do for now!)
>  
>  if (major != 0)
>      ret = major;
>  elseif (minor != 0)
>      ret = minor;
>  elseif (rev != 0)
>      ret = rev;
>  else
>      ret = text;
>  endif
>endfunction
>
>## Splits a version string into Major.Minor.Revision-Text.
>## Minor and Revision defaults to 0 ,while Text defaults to the empty string.
>function [major, minor, revision, text] = get_parts(v)
>  ## Default values
>  minor = revision = 0;
>  text = "";
>
>  ## Get text
>  dash = find(v == "-");
>  if (length(dash) > 0)
>      text = v(dash(1)+1:end);
>      v = v(1:dash(1)-1);
>  endif
>  
>  ## Get major, minor, and revision
>  dots = [find(v == "."), length(v)+1];
>  major = str2num( v(1:dots(1)-1) );
>  if (length(dots) >= 2)
>      minor = str2num( v( dots(1)+1:dots(2)-1 ) );
>  endif
>  if (length(dots) >= 3)
>      revision = str2num( v( dots(2)+1:dots(3)-1 ) );
>  endif
>  
>  ## Is everything okay?
>  if ( isempty(major) || isempty(minor) || isempty(revision) )
>      error("Input argument is not a valid version string.");
>  endif
>endfunction
>
>%!test 
>%! if (compare_version("2.6.1", "2.6.0") != 1) 
>%!     error("Test 1");
>%! endif
>
>%!test 
>%! if (compare_version("2.6", "2.6.0") != 0) 
>%!     error("Test 2");
>%! endif
>
>%!test
>%! if (compare_version("2.6-SVN", "2.6.0") != 1)
>%!     error("Test 3");
>%! endif
>
>## XXX: Is there a more easy way to test that a function returns an error?
>%!test
>%! test_failed = true;
>%! try
>%!     compare_version("2.6.0", "Monkey");
>%! catch
>%!     test_failed = false;
>%! end_try_catch
>%! if (test_failed)
>%!     error("Test 4");
>%! endif
>
>%!test
>%! if (compare_version("2.6.0-SVN2", "2.6.0-SVN1"))
>%!     error("Test 5");
>%! endif
>  
>


-- 
David Bateman                                address@hidden
Motorola Labs - Paris                        +33 1 69 35 48 04 (Ph) 
Parc Les Algorithmes, Commune de St Aubin    +33 6 72 01 06 33 (Mob) 
91193 Gif-Sur-Yvette FRANCE                  +33 1 69 35 77 01 (Fax) 

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